Manila motorists were warned of the danger of falling branches from trees lining six major avenues, said Corazon Davis, the government's regional environment chief.

Sixty-eight tiger's claw trees, known for their red flowers, have been cut down as a precaution while government workers were pruning infected branches from others to prevent them falling and potentially injuring motorists or damaging their vehicles, Davis said.

The wasps measuring about 1-1.5 centimeters (0.39-0.59 inches) lay eggs in young leaves and stems causing stress in the trees and eventual death.

Davis said similar infestations had been recorded in Laguna and Quezon provinces, both near Manila.

The exact origin of the Erythrina Gall Wasps and how they entered the Philippines is unknown. But the insects reportedly infected trees in Taiwan, Singapore, India, Hong Kong, China and Hawaii earlier this year, said Elpidio Rimando, pathologist at the environment department's ecosystem research and development bureau.

State-run University of the Philippines has sent samples of the insect to the Smithsonian Institute in the United States to get more information on their life cycle and devise measures to control its spread.